People lacking vital antioxidants and exposed to sunlight more likely to develop AMD

October 14, 2008

People who lack essential antioxidants, and who have high levels of sunlight exposure, have a higher risk of developing advanced macular degeneration (AMD), according to a study published today in the journal Archives of Ophthalmology. AMD is the leading cause of poor vision in the UK.

The EUREYE study, led by Astrid Fletcher, Professor of Epidemiology of Ageing at the London School of Hygiene & Tropical Medicine, is the first to report in human populations an adverse association between sunlight exposure and AMD in people with low levels of antioxidants. It is also unprecedented in the level of detail the researchers used, taking into account not only lifestyle and medical factors but even going so far as to estimate levels of cloud cover in each of the countries from which participants were recruited.

The eye is particularly vulnerable to the damaging effects of sunlight. Ultraviolet radiation is absorbed by the lens, but visible or "blue" light penetrates to the retina so allowing us to see. Protection against the harmful effects of blue light is provided by the antioxidant vitamins C and E, the carotenoids (lutein and zeaxanthin) which filter blue light, and zinc.

Animal and laboratory studies have previously shown that blue light may be a factor in the pathogenesis of AMD, but results have been inconsistent in the few studies that have investigated associations between sunlight exposure and AMD in human populations. Little attention has been paid to the possible interactions between antioxidant levels and light exposure, although it is thought that the adverse effects of sunlight may be mitigated by the protective effects of antioxidants.

4,753 participants aged 65 years were selected randomly in seven centres, Bergen in Norway, Tallinn in Estonia, Belfast in the UK, Paris-Creteil in France, Verona in Italy, Thessaloniki in Greece and Alicante in Spain. The average age of participants was 73.2 and 55% were women.

Blue light exposures tended to be higher in participants from centres in southern Europe while participants in an exclusively urban centre (Paris) had the lowest exposures.

Participants underwent fundus photography, and gave a blood sample for antioxidant analysis. They completed a residence and job history in advance, and attended a face-to-face interview. They were asked about their education, smoking and alcohol use, medical history, lifetime residence and level of sunlight exposure, including how much time they had spent outdoors between the hours of 9am and 5pm, and 11am and 3pm each day since they left school and throughout their working life.

Information was collected separately for summer and winter, and for different occupational time periods (including time spent looking after the home) and in retirement up to their current age. For each period, they were asked about their use of eyewear (glasses, contact lenses and sunglasses). The information on sunlight exposure and area of residence was sent to the University of East Anglia and combined with metrological information to estimate lifetime blue light exposure for each participant.

The results indicated that those with the lowest levels of antioxidants were most at risk of AMD due to blue light. In particular, the combination of blue light exposure and low levels of zeaxanthin, alpha tocopherol and Vitamin C was associated with a nearly four-fold likelihood of developing AMD. The researchers found that the associations of blue light in those with low antioxidant status appeared stronger at older ages, reaching a peak at 50-59 years.

The combination of blue light exposure and low concentrations of antioxidants in the blood was also found to be associated with the early stages of AMD, which are common in the population, and that exposures in middle age might be more damaging than at younger ages.

Professor Fletcher comments:
'In the absence of cost-effective screening methods to identify people in the population with early AMD, we suggest that recommendations on protecting the eyes, ensuring that diets contain the right nutrients and antioxidants, are targeted at the general population, and especially middle-aged people'.

'We are not telling people to stay out of the sun altogether. The benefits of sunlight are well documented, in particular its role in vitamin D synthesis. But if people want to avoid macular degeneration as they get older, they should avoid exposing their eyes to too much sunlight when they are outside, and take simple precautions, such as wearing a wide-brimmed hat and sunglasses,.

'Nor are we recommending that people should take vitamin supplements. It is perfectly possible to achieve the recommended dietary reference intakes for these essential antioxidants by following a balanced diet'.

Related Stories

If winter days get you down, you're not alone. You may have seasonal affective disorder, a type of depression triggered by the change of seasons. People with this disorder tend to feel depressed in the fall and winter, when ...

With winter in the northern hemisphere approaching, it's not uncommon for people to feel sluggish or moody. Those symptoms can be typical of someone experiencing seasonal affective disorder (SAD), a type of depression that ...

Elementary school science teaches us that in the sun, dark colors get hot while white stays cool. Now new research from Lawrence Berkeley National Laboratory (Berkeley Lab) has found an exception: scientists have determined ...

Researchers are interested in exploring how sunlight, sleep and screens (like those on computers and TVs) may affect those with attention-deficit/hyperactivity disorder (ADHD), says Dr. L. Eugene Arnold, a child psychiatrist ...

Newborn jaundice can be treated with filtered sunlight, providing a safe, inexpensive, low-tech solution to a health problem that now causes permanent brain damage or death in more than 150,000 babies in developing countries ...

Recommended for you

Researchers from the University of South Carolina, Duke University, University of Alabama at Birmingham, and Metabolon Inc. Research Triangle Park have discovered a new pathway in the liver that opens the door to treat non-alcoholic ...

New genetic research from an international team including McMaster University, University of Helsinki, Vilnius University and the University of Sydney, suggests that smallpox, a pathogen that caused millions of deaths worldwide, ...

Psoriasis is well-known for causing too many skin cells on elbows, knees, and across the body, but people living with psoriasis may also be at an increased risk of heart disease. Effects of overactive immune cells in the ...

In a new study, researchers have modified a rabies virus, so that it has a protein from the MERS virus; this altered virus works as a 2-for-1 vaccine that protects mice against both Middle East Respiratory Syndrome (MERS) ...

0 comments

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.